How can you define “over-discharge” and its effect on a battery?
A battery is over-discharged in case when the final voltage is lower than standard final voltage. Some of the consequences of over-discharging a battery are overuse of active material, degradation of the plate. If you recharge the battery after its over-charging there will be short failures.
A battery is over discharged in most circumstances when the battery falls below 1.75 volts per cell (VPC) under load, 10.50 volts for a 12 volt battery or 5.25 volts for a 6 volt battery. Some exceptions are permitted for short duration, high rate loads less than 1 hour. Battery life expectancy will be reduced and if the battery is over-discharged consistently ad will result in prematurely failure. In all cases, a battery should be recharged immediately after the discharge to prolong life.